The present invention relates generally to an adjustable headrest for a dental chair and more particularly to the means for moving the headrest to a selected position.
Generally, the headrest of a dental chair has a support which is journaled to one end of a tongue. The tongue, in turn, is slidably inserted into a slot in the backrest of the dental chair. This arrangement provides the headrest with two degrees of adjustment. In the first instant, the tongue can slide into and out of the headrest and in the second instant the headrest can be articulated about the tongue. Two locks are provided, one holding the tongue at its adjusted position with the respect to the backrest and the second for holding the headrest at its adjusted articulated position with respect to the tongue. Various releases are provided for manually unlocking and positioning the headrest at the desired adjusted position.
Typical of the prior art patents disclosing the degrees of motion of the headrest and various locking members are shown for example, in U.S. Pat. Nos. 2,740,467, 3,477,761, 3,603,642 and 3,936,091. Other patents illustrating different adjusting mechanisms and locks for adjustable dental chair headrests include German Pat. Nos. 23 26 255, 21 02 543 and 26 46 613.
According to the prior art, the problem to be solved by each of these patents, is the provision of a positive locking means which permits the adjustment of the tongue and the inclination of the headrest, the locks being relatively malfunction free, requiring a minimum of installation space and being quickly and easily unlocked to facilitate rapid adjustment of the headrest to any selected position.